Petroleum has become an essential part of our daily lives as it is important as a source of both energy and chemicals. There are, however, many problems associated with the recovery and processing of petroleum, such as the huge environmental impact associated therewith. In order to reduce the impact on environment, stringent policies and restrictions have been implemented by many countries on petroleum products. For example, in many countries, including the United States, strict regulations have been implemented relating to the amounts and types of sulfur compounds that can be included in motor gasoline and diesels.
These ever increasing demands for and stricter regulations on petroleum products poise inevitable challenge for the petroleum industry. Furthermore, the increasing supply of inferior petroleum sources, such as heavy and sour crude oils, requires major breakthroughs in refining technology to supply larger quantities of higher quality petroleum products to market. The recovery of petroleum from lower quality sources means that the petroleum that is recovered will likely include increased amounts of impurities, such as sulfur and metals, and greater percentages of heavy oil fractions. This in turn requires increased processing procedures designed to remove impurities and to convert the heavy fractions to more desirable and usable lighter fractions. Generally, the petroleum refining industry has relied upon conventional methods to clean and upgrade these lower quality petroleum feedstocks.
In general, conventional methods for cleaning and upgrading petroleum feedstock can be classified into two groups: hydrogenative and thermal methods. Hydrogenative methods, which can include hydrotreating and hydrocracking, typically employ hydrogen gas and a catalyst to remove impurities and convert the heavier fractions into light and middle-range petroleum products. Thermal methods, which can include coking and visbreaking typically do not utilize either hydrogen gas or a catalyst, instead relying upon relatively high temperatures for the conversion of heavier fractions. These conventional technologies have been proven and operated for long time.
Conventional methods, however, suffer from many limitations and drawbacks. For example, hydrogenative methods typically require large amount of hydrogen gas to achieve the desired level of upgrading and desulfurization conversion. Additionally, hydrogenative methods also require large amounts of catalyst, due to the frequent deactivation of catalyst. Thermal methods suffer from the production of large amount of coke as a byproduct and generally demonstrate limited success in the removal of impurities, such as sulfur and nitrogen, and can result in the production of large amounts of olefin and diolefin products, which must then be stabilized.
Thus, there exists a need to develop new methods for the upgrading of certain petroleum products that address and reduce the limitations and drawbacks noted above.